Piston



May 21, 1940. J. H. NICHOLSON PISTON I 2 Sheets-Sheet 1 Filed March 28,1939 Inventor aza nk% is wa By M 5 A ttorney J. H. NICHOLSON PISTON May21, 1940.

2 Sheets-Sheet 2 Filed Marbh 2a, 1939 QMQHIIIHIIIJIIIIIIMI In uentorAttorneys Patented May 21, 1940 UNITED STATES PATENT OFFICE 2 Claims.

The present invention relates generally to engines and more particularlyto new and useful improvements in the pistons and cylinders thereof.

The primary object of the invention is to provide, in a manner ashereinafter set forth, a piston and cylinder construction wherein theusual resilient rings are eliminated and through the medium of which thefriction between the piston and its cylinder will be materially reducedor substantially eliminated.

- Other objects of the invention are to provide an engine cylinder andpiston construction which will be comparatively simple, strong, durable,re-

liable in operation and which maybe manufactured at low cost.

All of the foregoing and still further objects and advantages of theinvention will become apparent from a study of the following specifica-50 tion, taken in connection with the accompanying drawings wherein likecharacters of reference designate corresponding parts throughout theseveral views, and wherein:

Figure 1 is a view in horizontal section through a piston and cylinderconstructed in accordance with the present invention, takensubstantially on the line l| of Fig. 4. a

Figure 2 is an elevational view of the piston.

Figure 3 is a top plan view of the piston.

Figure 4 is a vertical sectional view, taken substantially on the line44 of Fig. 1.

Figure 5 is a fragmentary view in vertical sec* tion through thecylinder. 1

Figure 6 is a detail view in elevation of one of the ball bearings.

Referring now to the drawings in detail, itwill be seen that theembodiment of the invention which has been illustrated comprises acylinder l of suitable dimensions. The walls of the cylinder I arefluted or vertically grooved, as at 2. The lands between the verticalgrooves 2 taper to knife edges, as at 3. It may be well to here statethat the vertical grooves in the cylinder l are substantiallysemi-circular.

Mounted for reciprocation in the cylinder [is a piston which isdesignated generallyby the reference numeral 4. The piston 4 is providedwith a wrist pin 5 to which a connecting rod 6 is coupled.

The piston 4 is vertically split, as at I. As best seen in Fig. 4 of thedrawings, the piston 4 also includes a threadedly mounted removable head8. It will be observed that-the head 9 and the upper end portion of thepiston 4 into which it is screwed are slightly tapered. Thus, thepiston'4 may be expanded if desired to obtain the correct fit in thecylinder I.

The piston 4 has formed vertically therein grooves 9 which are opposedto the cylinder wall grooves 2. The lands between the piston grooves 9also taper to a knife edge, as at l0. Mounted in the piston grooves 9are ball bearings Ii which travel in the cylinder wall grooves 2.Elements I! of suitable metal are provided for supporting the ballbearings II in the grooves 9. It will be observed that a single set ofballs II is provided on the lower end portion of the piston 4-and that adouble set of said balls are provided on the upper portion of saidpiston. A removable retaining ring l3 for the upper ball bearing Hissecured on the upper end of the piston 4.

It is thought that the operation of the invention will be readilyapparent from a consideration of the foregoing. Briefly, as the piston 4reciprocates in the cylinder l the ball bearings ll move therewith,traveling in the grooves 2 of said cylinder. The construction andarrangement is such that the walls ll substantially close and seal thespaces between the piston 4 and the cylinder I and at the same timefunction as bearings for greatly reducing friction and drag between saidpiston and cylinder. The upper balls prevent the escape of gases fromthe combustion chamber while the lower balls prevent the passage ofexcessive oil from the crank case. By screwing the slightly tapered head9 downwardly in the correspondingly shaped upper end portion of thepiston 4, said piston may be conveniently expanded to secure proper fitof the assemblage in thecylinder. The reference numeral l4 desi nates anexpansion ring in the lower portion of the piston 4.

It is believed that the many advantages of an engine piston and cylinderconstructed in accordance with the present invention will be readilyunderstood and although a preferred embodibeing substantiallysemi-circular, the lands bee tween the cylinder grooves and between thepiston grooves tapering to substantially knife edges, ball bearingsmounted on the piston in the grooves therein and operable in thecylinder grooves, and means for retaining said ball bearings againstlongitudinal movement in the piston rooves.

2. An engine comprising a cylinder having longitudinal grooves therein,a piston operable in the cylinder, said piston being longitudinallysplit and having longitudinal grooves therein opposed to the pistongrooves, a. tapered head threadedly

